The present invention relates to a metal laminate gasket with edge support shims to prevent upward expansion or deformation of a cylinder head of an engine.
In an engine having a plurality of cylinder bores arranged in one or a longitudinal direction, a plurality of bolt holes is arranged to surround the respective cylinder bores to tightly seal therearound. A gasket to be installed in this engine includes a plurality of sealing means around the cylinder bores, at which high surface pressure is formed when the gasket is tightened.
When the gasket is tightened between a cylinder head and a cylinder block by bolts, sealing means situated around the respective cylinder bores are compressed. In this respect, a bolt located in a middle portion of the engine operates to tighten two, i.e. right and left, longitudinal sides of the sealing means relative to the bolt. However, a bolt at the longitudinal end of the engine operates to tighten only one side of the sealing means, not two sides. Thus, the bolts at the longitudinal ends operate to tighten the sealing means at a pressure generally twice as much as that at the middle portion of the sealing means.
The unbalanced tightening pressure causes the middle portion of the cylinder head to project upwardly. As a result, equal sealing pressure is not obtained at the sealing means.
In U.S. Pat. No. 4,776,073, a gasket is provided with two kinds of surface pressure regulation plates installed around different holes to be sealed.
In U.S. Pat. No. 5,215,316, a gasket for an open deck type engine is provided with a thin metal plate, which is located above a main body to surround a water passage situated between cylinder walls and the main body. The thin metal plate provides surface pressure outside the entire water passage.
In the conventional gasket, a thin metal plate is installed around a hole to be sealed to provide high surface pressure around the hole. However, the thin metal plate is not used for other purposes.
Accordingly, one object of the invention is to provide a metal laminate gasket, which can provide by tightening bolts substantially equal surface pressure to all sealing means formed around the cylinder bores.
Another object of the invention is to provide a metal laminate gasket as stated above, which can substantially prevent deformation of a cylinder head caused by unbalanced surface pressure on the sealing means.
A further object of the invention is to provide a metal laminate gasket as stated above, which can be easily and economically manufactured.
Further objects and advantages of the invention will be apparent from the following description of the invention.